Mauricio,
No doubt the airlines do not have any way of checking the validity of residency info they enter into the system, that would be done here in the DR at some later date.
The airline is just performing their due diligence - no return ticket, why not? Oh you are a resident, kickity kick, good to go. The flight manifest listing all passengers is then sent to the DR after the gate closes and arrives usually before the flight is in the air. No return ticket, then the residency info entered by the airline appears next to the passenger name.
Voila, with the click of a button, that residency information could be verified if there is a previous entry in the DR residency database or added as new info subject to verification at a later time. Eventually, when the DR swipes a passport, the classification of that traveler will be displayed as a tourist, visa entry or resident.
We can probably safely extrapolate into the future and say with some degree of confidence that the airlines will soon pick up on the pattern of last minute purchased return tickets that are subsequently cancelled for a cash refund. Because the airlines have zero interest in acting as a temporary facilitation agent, if the practice becomes widespread, then refunds on the return portion of a trip will be changed to credits to be used on a future flight. Hanging onto your money is all the airline really cares about.
I think you are extrapolating too much.